Nasa scientists have begun initial examinations of the Stardust space capsule, following its return to Earth after a journey of more than 4.63 billion km.
The capsule, carrying a small but precious cargo of comet dust, survived a fiery return to Earth early Sunday, parachuting to a soft landing in America's Utah desert landing zone after a seven-year journey.
The capsule represents the first attempt to bring back samples of space dust from beyond the Moon.
Scientists hope the microscopic comet samples collected contained in the capsule will help unlock some of the biggest secrets of the universe.
It is thought the particles collected by Stardust date back to before the solar system was born, or about 4.5 billion years ago.
"We visited a comet, grabbed a piece of it, and landed here this morning"
Don Brownlee, principal investigator for the Stardust mission
"We visited a comet, grabbed a piece of it, and landed here this morning," said Don Brownlee, an astronomy professor with the University of Washington who is principal investigator for the Stardust mission. "It was a real thrill."
Earlier the main Stardust spacecraft jettisoned its cargo as it flew past the Earth, before heading on to a permanent orbit around the sun.
According to Nasa, the speed of the 46 kg capsule as it streaked into the Earth's atmosphere at 46,440km per hour was the fastest of any human-made object.
Stardust's fiery return was seen in the night sky
Plunging towards the Earth, the capsule was visible to many residents in the northwestern United States as a bright streak in the night sky.
The subsequent landing was textbook-perfect, with the spacecraft releasing it's initial parachute at about 32km and descending for a gentle landing in the Utah desert.
Within an hour the capsule had been picked up by helicopter, wrapped in a protective covering and flown to the US Army Dugway Proving Ground before it is taken to a Nasa lab in Houston, Texas.
Scientists believe the material snatched from the trail of a comet could provide dramatic information about the birth of the solar system and the origins of life on Earth.
Launched in 1999, the 385kg probe circled the Sun twice and then flew in January 2004 by comet Wild 2, which was located next to Jupiter at the time.
Stardust was sent on a close encounter with comet Wild 2
During the often hazardous journey, the spacecraft first deployed a shield to protect itself from gases and space dust contained in the halo of the comet.
It then flew within 240km of Wild 2, catching samples of comet particles and scoring detailed pictures of Wild 2's pock-marked surface.
The 72 pictures of Wild 2 taken by the probe show its rugged surface, including craters as well as about 20 "geysers" spewing gas and dust.
During 195 days of the flight, Nasa engineers used a collector to gather inter-stellar dust that will allow scientists to study the make-up of stars.
Stardust sent back dramatic pictures of the comet
The special collector a unique substance known as aerogel that can trap the particles and store the precious cargo safely until it is returned to Earth.
Mary Cleave, associate administrator for Nasa's Science Mission Directorate, said the load Stardust returned to Earth could help space explorers on many future missions.
"Comets are some of the most informative occupants of the solar system," she said.
"The more we can learn from science exploration missions like Stardust, the more we can prepare for human exploration to the Moon, Mars and beyond."